1. Field of the Invention
This invention relates to an image forming apparatus, and particularly to an image forming apparatus having an accessible internal space for accommodating printed sheets output the apparatus.
2. Discussion of the Background
Copying machines and facsimile machines are examples of typical image forming apparatuses that include a scanner for reading an image from an original sheet and a printer for printing data on a recording sheet. The copying machines generally have a flat scanner able to copy pages of bound documents, such as books. Both the copying machines and facsimile machines are able to accommodate loose-leaf sheets. Recently, a so-called multi-function peripheral (MFP) device has been introduced that is capable of performing all of the functions of, for example, facsimile, copying, and printing machines. MFP devices with a flat scanner are less common.
Generally, there are two paper ejection methods performed after completion of the printing operation in the above-mentioned typical image forming apparatus. One method ejects the printed sheets in a horizontal direction to a region for containing ejected sheets. This method is referred to as a "straight sheet ejection method." The other method transfers the sheets upwards and ejects the sheets face-down, and is referred to as a "face down ejection method."
A printer portion of the image forming apparatus can be miniaturized by applying the face-down ejection method. However, when the apparatus includes a flat scanner, the flat scanner limits the miniaturization potential of the apparatus due to a size of the scanner's platen, or contact glass. Thus the flat scanner has a relatively large footprint.
When the image forming apparatus has a structure in which a printed sheet is ejected to an area outside of the apparatus' footprint, an extra area is disadvantageously needed to accommodate printed sheets external to the space occupied by the apparatus.
On the other hand, as presently observed by the inventors, when the image forming apparatus includes a flat scanner situated on a printer having a relatively small extension surface (i.e., smaller footprint), the above-mentioned extra area can be eliminated. Specifically, when a scanner capable of scanning a bound document (i.e., a book-mode scanner) is mounted on a printer in such a way that the front of the scanner hangs over the front of the printer, a space under where the scanner overhangs and extends beyond the front of the printer is vacant and can therefore be used as a space for sheet ejection and retention.
As identified by the present inventors, when the scanner is a book-mode scanner that requires a relatively large horizontal flat surface for accommodating original documents, the book-mode scanner may have a larger surface area than that of the printer. Furthermore, the scanner's weight is distributed and therefore if only partially supported by a smaller printer, the apparatus may be top heavy and unstable, particularly when the image forming apparatus is used in an office environment, where different objects may be placed on the scanning apparatus. Furthermore, the inherent weight of the scanner may cause warpage of the scanner's platen, because not all edge surfaces of the scanner may be supported by the smaller printer. Consequently, the present inventors have identified that if the book-scanner and smaller printer are combined so as to provide an internal, accessible space for capturing ejected sheets, then additional counter measures are in order to provide appropriate support for the scanner, and provide for a mechanically stable apparatus.